Many electronic devices which use integrated circuits for the processing of analog and digital signals have to convert analog signals provided from independent units into digital signals or have to convert the same analog signal into a digital signal to satisfy requests from several independent units.
In these cases, since the requests for conversion can be almost simultaneous, i.e., concurrent, the prior art provides for the use of a plurality of analog/digital converters.
For example, in the conversion structure schematically illustrated in FIG. 1, two distinct analog/digital converters C_1, C_2 are used, each of which is provided for converting a respective analog signal VIN1, VIN2 into a digital signal. Request to convert the analog signal VIN1 is, for example, sent to converter C_1 from a first unit (not shown) by means of a conversion request signal CONVREQ1. After completion of the conversion, converter C_1 makes available, i.e. writes, a digital code resulting from the digital conversion of the analog signal VIN1 on an assigned bus OUTBUS1. Similarly, the request to convert the analog signal VIN2 is sent to converter C_2 from a second unit (not shown) and independent from the first unit, by means of a conversion request signal CONVREQ2. At the end of this conversion, circuit C_2 makes available, on an assigned bus OUTBUS2, a digital code resulting from the digital conversion of the analog signal VIN2.
In the structure illustrated in FIG. 1, a situation without a system clock is shown, so that the two converters C_1, C_2 use a clock signal generated locally by a respective oscillator CLK_GEN included in each of them. A detailed description of the functioning of such converters C_1 and C_2 is, for example, given in the European patent application EP 1583242.
As is known, analog/digital converters absorb energy even when they are not used to carry out their functions and occupy relatively large areas of the integrated circuit. For this reason, a conversion system of the type illustrated in FIG. 1 is unfavorable. Furthermore, the use of this architecture becomes impractical if there is a considerable number of analog signals to be converted and/or number of requesting units. This happens, for example, with mobile phones where size requirements are crucial and numerous analog signals normally have to be converted for a plurality of requesting units.